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Awareness of declining memory occurs 2 to 3 years before dementia onset

Analysis of three longitudinal studies indicated awareness of memory decline begins approximately 2 to 3 years prior to dementia onset and is associated with transactive response DNA-binding protein 43 pathology, tau tangles and gross cerebral infarcts.

“Progressive loss of memory is a central feature of dementia, but affected persons are not always aware of this impairment, and despite much research it remains uncertain how common unawareness of memory impairment is in persons with dementia, when it develops, or why some are apparently affected more than others. Unawareness has been associated with dementia severity in some cross-sectional studies but not others,” Robert S. Wilson, PhD, of Rush Alzheimer’s Disease Center of Rush University in Chicago, and colleagues wrote.

Researchers evaluated data from three longitudinal clinical-pathologic cohort studies for 2,092 older adults who had no memory or cognitive impairment at baseline. Clinical classification of dementia and self-rating and performance testing of memory occurred during annual evaluations over a mean 7.7 years of follow-up.

Overall, memory ratings were modestly correlated with memory performance (P < .001), so researchers regressed individuals’ memory performance on their memory ratings to gauge longitudinal indicators of memory awareness.

Among 239 individuals who developed dementia, episodic memory awareness was stable until a mean of 2.6 years before dementia onset. Subsequently, memory awareness rapidly declined with a mean annual change of –0.32 (95% CI, –0.37 to –0.28).

Older age at baseline was associated with later onset of memory unawareness, according to researchers.

Neuropathologic examination of 385 individuals who died during the study period indicated associations between transactive response DNA-binding protein 43 pathology, tau tangles, gross cerebral infarcts and decline in memory awareness. No decline in memory was observed when these pathologies were absent.

“The results suggest that declining awareness of memory impairment is an essentially inevitable manifestation of late-life dementia,” the researchers concluded. – by Amanda Oldt

Disclosure: Wilson reports serving as a Consulting Editor for Aging, Neuropsychology, and Cognition, Psychology and Aging, and Neuropsychology; serving as a consultant for Pain Therapeutics, Inc.; and receiving research support from the NIH, the Alzheimer’s Association and Zinfandel Pharmaceuticals. Please see the full study for a list of all other authors’ relevant financial disclosures.